淺拷貝是指拷貝對(duì)象時(shí)僅僅拷貝對(duì)象本身（包括對(duì)象中的基本變量），而不拷貝對(duì)象包含的引用指向的對(duì)象。深拷貝不僅拷貝對(duì)象本身，而且拷貝對(duì)象包含的引用指向的所有對(duì)象。舉例來(lái)說(shuō)更加清楚：對(duì)象A1中包含對(duì)B1的引用，B1中包含對(duì)C1的引用。淺拷貝A1得到A2，A2 中依然包含對(duì)B1的引用，B1中依然包含對(duì)C1的引用。深拷貝則是對(duì)淺拷貝的遞歸，深拷貝A1得到A2，A2中包含對(duì)B2（B1的copy）的引用，B2 中包含對(duì)C2（C1的copy）的引用。

package Clone;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

/**
 * @ClassName: CopyDemo
 * @Author sandy.n.hao
 * @Date: 2019-07-10
 * @Version v1.0.0
 * @Description: //TODO
 */

public class CopyDemo {

    public static void main(String[] args) {

        Person p1 = new Person("Sandy",18);
        Person p2 = new Person("Monica",20);

        Map<String,Object> map1= new HashMap();
        Map<String,Object> temp= new HashMap();

        map1.put("first",p1);

        temp.put("temp","temp");

        Map<String,Object> map2 = new HashMap();
        Map<String,Object> map3 = new HashMap();

        System.out.println("拷貝前：");
        System.out.println("map1: "+map1);
        System.out.println("map2: "+map2);
        System.out.println("map3: "+map3);


        /*
         * 淺拷貝
         */
        map2.putAll(map1);

        /*
         * 深拷貝
         */
        map3 = Utils.DeepClone(map1);


        //拷貝后
        System.out.println("拷貝結(jié)果：");
        System.out.println("map1: "+map1);
        System.out.println("map2: "+map2);
        System.out.println("map3: "+map3);

//        ((Map)(map1.get("first"))).put("final","final");
        ((Person)(map1.get("first"))).setName("Coco");
        ((Person)(map1.get("first"))).setAge(20);

        System.out.println("修改后：");
        System.out.println("map1: "+map1);
        System.out.println("map2: "+map2);
        System.out.println("map3: "+map3);
    }

    /*
    內(nèi)部類實(shí)現(xiàn)序列化
     */
    public static class Person implements Serializable
    {
        private static final long serialVersionUID = 8656128222714547171L;
        transient private String name;
        private int age;

        Person(String name,int age){
            this.name= name;
            this.age=age;
        }

        public int getAge() {
            return age;
        }

        public String getName() {
            return name;
        }

        public void setAge(int age) {
            this.age = age;
        }

        public void setName(String name) {
            this.name = name;
        }

        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

}

package com.sandy.DeepAndShallowCopy;

import com.sun.xml.internal.messaging.saaj.util.ByteInputStream;

import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;


public class Utils {

    public static <T extends Serializable> T DeepClone (Object obj){
        T cloneObj = null;
        try{
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
            objectOutputStream.writeObject(obj);
            objectOutputStream.close();

            ByteInputStream byteInputStream = new ByteInputStream(byteArrayOutputStream.toByteArray(),byteArrayOutputStream.size());
            ObjectInputStream objectInputStream = new ObjectInputStream(byteInputStream);
            cloneObj = (T) objectInputStream.readObject();
            objectInputStream.close();


        }catch (Exception e){
            e.printStackTrace();
        }
        return cloneObj;
    }
}

輸出：

拷貝前：
map1: {first=Person{name='Sandy', age=18}}
map2: {}
map3: {}
拷貝結(jié)果：
map1: {first=Person{name='Sandy', age=18}}
map2: {first=Person{name='Sandy', age=18}}
map3: {first=Person{name='null', age=18}}
修改后：
map1: {first=Person{name='Coco', age=20}}
map2: {first=Person{name='Coco', age=20}}
map3: {first=Person{name='null', age=18}}

map3通過(guò)序列化的方式實(shí)現(xiàn)了深拷貝，name用transient，未進(jìn)行序列化，是實(shí)現(xiàn)深拷貝。